On Sunday night, half a dozen members of the Netherlands squad were having a few quiet drinks at a Rio de Janeiro rooftop bar. Their press officer was with them, so this was obviously happening with the blessing of Louis van Gaal, who can be very strict about these things. (It didn't look as if anyone had any alcohol.)

A regular at the bar told us that the Dutch, who had been staying in a nearby hotel on Ipanema beach until Monday (they hadn't been able to book the rooms for longer), had come quite often to escape the confines of their rooms and chill a bit. So far, so unremarkable. That's just the sort of thing the Dutch do.

But there was something interesting about this group. All the players were wearing dark tops, and some also had baseball caps, with the overall effect that they almost disappeared into the darkness. The only Dutchman who wasn't at all concerned with keeping a low profile was Dirk Kuyt. The 33-year-old wore a white and orange training jacket, and his blond locks were visible from the distance.

Maybe, at his age, he's simply past caring. Or maybe he actually enjoyed a bit of attention during what promises to be his last tournament. Kuyt, it's fair to say, has played a surprisingly big role in the Oranje's progress to the semifinals. He's been a starter in their past three games and should feature again against Argentina on Wednesday.

Dirk Kuyt's versatility and commitment have been priceless for the Dutch this summer.

The Fenerbahce striker has never been the sort of forward that the Dutch truly appreciate. His game is based on effort, endurance and positional intelligence. As a centre-forward, he's always had better players ahead of him and on the flanks; various coaches have preferred true wingers. Kuyt has been a different sort of specialist: a defensive wide forward. At club level, Rafael Benítez used him most effectively in that hybrid role during his time at Liverpool (2006-12) -- "Mr Duracell," the Spaniard used to call him.

Under Marco van Basten, Kuyt played very well on the right in a counterattacking 4-2-3-1 Dutch side at Euro 2008. At the World Cup in South Africa two years later, his work rate contributed, as Bert van Marwijk's well-organised but largely uninspiring side made it to the final. His involvement in Poland/Ukraine 2012, where internal rifts and poor performances resulted in an early exit, only amounted to 12 minutes in two substitute appearances.

Few expected the veteran from Katwijk aan Zee, a small city on the North Sea coast, to see so much action in Brazil, but perhaps we should have known something was up after one of the training sessions before the opening game against Spain. Van Gaal had requisitioned Kuyt from the reserves to train with the first-team forwards in Estadio da Gavea -- as a defender. Arjen Robben, Wesley Sneijder, Robin van Persie and a couple of others always outnumbered a two-, three- and four-man defence marshalled by Kuyt as the main centre-back, but they hardly got behind them to score any goals. Kuyt's men were too well positioned. The Dutch media later reported that since May van Gaal had been practising with the former Feyenoord man in various defensive positions.

It's easier to list the positions he hasn't played at this World Cup. Apart from goalkeeper and the centre of defence, Kuyt has featured everywhere on the pitch for van Gaal. Against Mexico in the round of 16, Kuyt was used in four different roles by the 62-year-old coach. "He is fantastic; he is ready for everything, from the first to the last second," Kuyt said about van Gaal after the penalty win over Costa Rica.

All those frequent tactical changes are only possible because in Kuyt, the future Man United manager has a player who will selflessly do any task asked of him, and he will do it with maximum effort. "Robben might be the star, Sneijder might be the tragic hero who has sacrificed himself ... but the symbol of this team is Dirk Kuyt," said Johan Cruyff, the high priest of Oranje, who never had too much time for hard workers in the past. "You are blessed with someone like Kuyt. You can go everywhere with him, tactically."

The son of a fisherman -- Kuyt himself worked on the trawlers as a teenager before starting his career at Utrecht -- represents the more pragmatic, physical Rotterdam style, but he has ironically become the last link to the old idea of Total Football, too. Dutch footballers were supposed to play in any position and interchange frequently, according to the 1970s textbook, but Cruyff et al never had good, honest runners such as Kuyt in mind.

Yet the former Barcelona coach seems to have relaxed his criteria in line with the changed mood in the Netherlands. "They have given up on the way of football we developed," the 67-year-old said. "But something has come in the place of that creativity and dominance. And it works. It is direct and effective, and it is built on passion and team spirit."

The actual football is being played by the three guys further up the pitch. Kuyt's importance, however, cannot be underestimated. Not only is his ultra-professional attitude exemplary, but he also helps the dressing room with his sunny and endearingly positive disposition. It's telling that van Gaal appointed him vice-captain when he took over; Kuyt continued in this role despite getting little playing time in the World Cup qualifiers.

Kuyt's importance, stamina and versatility cannot be underestimated.

On the occasion of his 100th cap for the Netherlands, the round of 16 clash with Mexico, van Persie presented Kuyt with a little gift and gave a short speech. Kuyt became only the seventh "centurion" in the history of the KNVB (Royal Dutch Football Association), and the day coincided with the seventh anniversary of his father's death, too.

"I knew that my father would have been proud, but not just for me -- for all the players and the staff," he said. That might not have been the last emotional, historic day for the second-oldest player (behind Germany's Miroslav Klose) left in the competition. "We have a lot of quality, and we will show it to Argentina."

Having come this far, Mr. Duracell is not about to slow down now.

Raphael Honigstein is ESPN FC's German football expert and a regular guest on ESPN FC TV. He also writes for the Guardian. Twitter: @honigstein.